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Confusion with relating the sensor output voltages from its datasheet

floppy32

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From the datasheet of this acccelerometer (ADXL335) I cant figure out the x y z outputs' voltage ranges. Is it mentioned in the datasheet what output voltages corresponds to -3g and +3g?

And how can I calculate the voltage output corresponding to 500µg?
 

wwfeldman

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data sheet page 3:

Sensor Input Measurement range (typical) +/- 3.6g

Sensitivity (typical) 300 mV/g

Zero g Bias Level (typical) 1.5 V

These tell me that an output of 1.5 V means no acceleration
and that the acceleration is measured at 0.3 V/g, so 1.8 V is 1 g in + direction, probably up from the chip's point of view,
and 1.2 V is 1 g in - direction, probably down from the ships point of view.

Page 5 pin functions and function descriptions has a drawing of the chip, with x, y, and z axis shown in the center of the drawing,
thereby defining the + and - directions in 3 space.

500 ug * 0.3 V/g = 150 uV
 

FvM

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I agree that the datasheet is very clear about expectable output voltage.

But if you plan to measure 500 ug acceleration, you should carefully read the datasheet info about noise density and temperature drift.
 

c_mitra

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500 ug = 500 x1e-6x980 cm.sec^(-2) = 0.49 cm.sec^(-2) ---> bit small but can be measured.

As others have pointed out earlier, the output will be around 150 uV. Bit small but can be measured accurately with a decent amplifier.

As others have mentioned before, you also need to pay attention to the noise. That essentially means that you cannot make two measurements in quick succession.
 

Akanimo

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Hi,

A lot of the relationships are ratiometric which means that you have to set out your specifications first.

What is your supply voltage?
 

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